| Date | Fri, 8 May 2020 22:27:50 +0900 | From | Masami Hiramatsu <> | Subject | Re: [patch V4 part 4 02/24] x86/int3: Avoid atomic instrumentation |
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On Tue, 05 May 2020 15:49:28 +0200 Thomas Gleixner <tglx@linutronix.de> wrote:
> From: Peter Zijlstra <peterz@infradead.org> > > Use arch_atomic_*() and READ_ONCE_NOCHECK() to ensure nothing untoward > creeps in and ruins things. > > That is; this is the INT3 text poke handler, strictly limit the code > that runs in it, lest it inadvertenly hits yet another INT3. > > Reported-by: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
> --- > arch/x86/kernel/alternative.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > --- a/arch/x86/kernel/alternative.c > +++ b/arch/x86/kernel/alternative.c > @@ -960,9 +960,9 @@ static struct bp_patching_desc *bp_desc; > static __always_inline > struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp) > { > - struct bp_patching_desc *desc = READ_ONCE(*descp); /* rcu_dereference */ > + struct bp_patching_desc *desc = READ_ONCE_NOCHECK(*descp); /* rcu_dereference */ > > - if (!desc || !atomic_inc_not_zero(&desc->refs)) > + if (!desc || !arch_atomic_inc_not_zero(&desc->refs)) > return NULL; > > return desc; > @@ -971,7 +971,7 @@ struct bp_patching_desc *try_get_desc(st > static __always_inline void put_desc(struct bp_patching_desc *desc) > { > smp_mb__before_atomic(); > - atomic_dec(&desc->refs); > + arch_atomic_dec(&desc->refs); > } > > static __always_inline void *text_poke_addr(struct text_poke_loc *tp) >
-- Masami Hiramatsu <mhiramat@kernel.org>
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